Water Crisis Due to Dam Sedimentation - DTE - 16/01/23

Context:
The United Nations Institute for Water, Environment and Health showed in its report that about 50,000 large dams across the world will lose 24-28% water storage capacity by 2050 due to sediment trapped in them. These water reservoirs have already lost about 13-19% capacity to sedimentation.
Relevance:
GS3
About:
-Sedimentation in dams refers to the accumulation of sediments, such as sand, gravel, and silt, at the bottom of a reservoir created by a dam. This sediment can build up over time, reducing the overall storage capacity of the reservoir.

->Dredging: Dredging is the process of removing sediments, such as sand, gravel, and silt, that has accumulated at the bottom of a reservoir. It can be done using various methods, such as mechanical dredging with a dredge machine or hydraulic dredging with a high-pressure water jet.

->Causes of Sedimentation:
a. Erosion Upstream of the Dam: When soil and rock is washed away from the area upstream of the dam, it can be carried downstream and deposited in the reservoir.
b. Runoff from Urban and Agricultural Areas: The increased use of land for human activities, such as urbanization and agriculture, can lead to increased runoff of sediment into the reservoir.
c. Natural Processes: Sedimentation can also occur naturally through processes such as weathering and erosion.
d. Climate Change: Climate change causes more intense and frequent rainfall events and also causes snowmelt earlier which can lead to increased erosion and sediment runoff into the reservoir.
e. Deforestation
f. Poor dam maintanance

->Consequences of Dam Sedimentation:
1. Environmental:
Reduced water storage capacity in the reservoir, which can lead to water shortages for downstream users and the loss of habitat for aquatic species. Increased risk of dam failure as the sediment can cause the dam to become unstable.
2. Economic:
Increased cost of maintenance and dredging to remove the sediment. Loss of hydroelectric power generation due to reduced water flow through the dam. Reduced irrigation and water supply for agriculture and industry.
3. Damage to Dam Structure and Turbines:
The accumulation of sediment at the bottom of the reservoir can cause scouring, or erosion, of the dam's foundation, which can weaken its structural integrity and increase the risk of failure. Sediment can also clog the turbine intake, which can reduce the efficiency of hydroelectric power generation and require costly maintenance to remove the sediment.

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